(a) Technical Field
The present disclosure relates to a touch sensor device. More particularly, the present invention relates to a flexible touch sensor device.
(b) Description of the Related Art
An electronic device such as a liquid crystal display (LCD), an organic light emitting diode display (OLED display), and an electrophoretic display may include a touch sensing function such that it is capable of interaction with a user. A touch sensing function determines whether an object (a user's finger, touch pen, etc.) touches a screen, and information about the touch, by sensing a change of pressure, light, etc., that occurs on a screen in the display device when a finger or a touch pen contacts the screen to write a character, draw a picture, etc.
The touch sensing function of the several electronic devices may be realized through a touch sensor. The touch sensor may be classified into various types such as a resistive type, a capacitive type, an electromagnetic (EM) type, and an optical type.
For example, the capacitive touch sensor includes a sensing capacitor formed by a sensing electrode which may transfer a sensing signal, and senses a change in capacitance of the sensing capacitor generated when a conductor such as a finger approaches the touch sensor to determine the existence of a touch, a touch position, and the like. The capacitive touch sensor may include a plurality of touch electrodes disposed in a touch sensing region sensing the touch and touch wiring connected to the touch electrodes. The touch wiring may transmit a sensing input signal to the touch electrode and transmit a sensing output signal of the touch electrode generated depending on the touch to a touch driver.
The touch sensor may be installed in the display device (an in-cell type), formed on an outer surface of the display device (an on-cell type), or attached to a separate touch sensor panel to the display device (an add-on cell type). Particularly, in a case of the flexible display device, a method (add-on cell type) of adhering a film in which the touch sensor is formed or forming and adhering a separate touch sensor device of a plate shape on the display panel may be used.
When electronic devices such as the display device and the touch sensor device use a glass substrate that is heavy and easily damaged, its portability and scalability to a large-scale screen display get limited. Thus, recently, a flexible electronic device which is light, durable, more impact-resistant, and having a plastic substrate with high flexibility such as PI has been actively developed. In this case, the flexible touch sensor device may include a portion that is exemplarily bendable, foldable, rollable, stretchable in at least one direction, or is elastic and is able to be deformed.
The flexible touch sensor device includes a plurality of touch electrodes, and the touch electrodes may have flexibility to not generate a failure after deformation.
As a material for the touch electrode having flexibility, various materials such as metal nanowire (e.g., silver nanowire or AgNW), carbon nanotubes, graphene, a metal mesh, and a conductive polymer have been actively developed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.